See: typescript-eslint/typescript-eslint#9571

It seems that when you don't have extraFileExtensions: [".vue"] in languageOptions, the Vue plugin seems to modify it at runtime to add/remove .vue from it, but whenever it does so, it seems to trigger a full project service reload, which is very slow. We might want to add this to the shared config?

You can see that by using DEBUG=* eslint and looking for reload projects.